The present invention relates to a disk jacket receiving a photo-magnetic disk, or a disk-like medium and more particularly to an opening and closing mechanism of a recording and reproducing head insert opening of the jacket.
A conventional floppy disk, having a diameter of 3 or 3.5 inches, is protected from dust by a cover jacket. The jacket has a recording and regenerating or reproducing head insert opening, and the opening is closed by a cover to protect an information recording surface of the floppy disk from dust when the floppy disk is in an inoperative position.
Such a conventional disk jacket is shown in FIG. 9. The disk jacket 40 has a central spindle insert opening 41 and a head insert opening 42. A cover plate 43 made of a thin metal sheet has an opening 44 and is slidable on the jacket 40. Between the cover 43 and the jacket 40, a tension spring 45 is connected to maintain the cover 43 to a direction A shown in FIG. 9, to close the opening 42 of the jacket 40 in the inoperative position of the jacket 40. When the jacket 40 is set in a recording and regenerating apparatus, the cover plate 43 is pushed to a direction shown by an arrow B in FIG. 9, until the jacket opening 42 is aligned with the opening 44 of the cover plate 42 to allow inserting of the recording and regenerating head not shown.
When such a mechanism is utilized to a large recording and regenerating optical head of a photo disk apparatus a photo-magnetic disk apparatus, radial dimension of the jacket opening 44 must be increased to cover all information recording portion of the disk so that a width of the cover plate 43, in the radial direction of the disk, must be increased. Also, when the disk dimension is increased, the radial dimension of the cover plate must be increased.
In every case, the conventional cover plate having the cantilever support slide mechanism guided by a jacket edge portion can not be adapted to such increased dimension so that sliding of the cover plate can not be smoothly performed. Further, the opening 42 can not allow sufficient radially inward movement of the head, especially when the head is large.